Use downgrades when fixing dbscheme mismatches where possible. (#765)

Author: alexet

extensions/ql-vscode/src/cli.ts

@@ -131,6 +131,12 @@ export class CodeQLCliServer implements Disposable {
    */
   private static CLI_VERSION_WITH_LANGUAGE = new SemVer('2.4.1');
 
+  /**
+   * CLI version where `codeql resolve upgrades` supports
+   * the `--allow-downgrades` flag
+   */
+  private static CLI_VERSION_WITH_DOWNGRADES = new SemVer('2.4.4');
+
   /** The process for the cli server, or undefined if one doesn't exist yet */
   process?: child_process.ChildProcessWithoutNullStreams;
   /** Queue of future commands*/
@@ -662,15 +668,19 @@ export class CodeQLCliServer implements Disposable {
    * Gets information necessary for upgrading a database.
    * @param dbScheme the path to the dbscheme of the database to be upgraded.
    * @param searchPath A list of directories to search for upgrade scripts.
+   * @param allowDowngradesIfPossible Whether we should try and include downgrades of we can.
    * @param targetDbScheme The dbscheme to try to upgrade to.
    * @returns A list of database upgrade script directories
    */
-  resolveUpgrades(dbScheme: string, searchPath: string[], targetDbScheme?: string): Promise<UpgradesInfo> {
+  async resolveUpgrades(dbScheme: string, searchPath: string[], allowDowngradesIfPossible: boolean, targetDbScheme?: string): Promise<UpgradesInfo> {
     const args = ['--additional-packs', searchPath.join(path.delimiter), '--dbscheme', dbScheme];
     if (targetDbScheme) {
       args.push('--target-dbscheme', targetDbScheme);
+      if (allowDowngradesIfPossible && await this.supportsDowngrades()) {
+        args.push('--allow-downgrades');
+      }
     }
-    return this.runJsonCodeQlCliCommand<UpgradesInfo>(
+    return await this.runJsonCodeQlCliCommand<UpgradesInfo>(
       ['resolve', 'upgrades'],
       args,
       'Resolving database upgrade scripts',
@@ -744,6 +754,10 @@ export class CodeQLCliServer implements Disposable {
     return (await this.getVersion()).compare(CodeQLCliServer.CLI_VERSION_WITH_LANGUAGE) >= 0;
   }
 
+  public async supportsDowngrades() {
+    return (await this.getVersion()).compare(CodeQLCliServer.CLI_VERSION_WITH_DOWNGRADES) >= 0;
+  }
+
   private async refreshVersion() {
     const distribution = await this.distributionProvider.getDistribution();
     switch (distribution.kind) {

extensions/ql-vscode/src/run-queries.ts

@@ -294,7 +294,7 @@ async function checkDbschemeCompatibility(
   const searchPath = getOnDiskWorkspaceFolders();
 
   if (query.dbItem.contents !== undefined && query.dbItem.contents.dbSchemeUri !== undefined) {
-    const { finalDbscheme } = await cliServer.resolveUpgrades(query.dbItem.contents.dbSchemeUri.fsPath, searchPath);
+    const { finalDbscheme } = await cliServer.resolveUpgrades(query.dbItem.contents.dbSchemeUri.fsPath, searchPath, false);
     const hash = async function(filename: string): Promise<string> {
       return crypto.createHash('sha256').update(await fs.readFile(filename)).digest('hex');
     };
@@ -348,7 +348,7 @@ async function compileNonDestructiveUpgrade(
   if (!query.dbItem?.contents?.dbSchemeUri) {
     throw new Error('Database is invalid, and cannot be upgraded.');
   }
-  const { scripts, matchesTarget } = await qs.cliServer.resolveUpgrades(query.dbItem.contents.dbSchemeUri.fsPath, searchPath, query.queryDbscheme);
+  const { scripts, matchesTarget } = await qs.cliServer.resolveUpgrades(query.dbItem.contents.dbSchemeUri.fsPath, searchPath, true, query.queryDbscheme);
 
   if (!matchesTarget) {
     reportNoUpgradePath(query);

extensions/ql-vscode/src/upgrades.ts

@@ -171,7 +171,8 @@ export async function upgradeDatabaseExplicit(
   }
   const upgradeInfo = await qs.cliServer.resolveUpgrades(
     db.contents.dbSchemeUri.fsPath,
-    searchPath
+    searchPath,
+    false
   );
 
   const { scripts, finalDbscheme } = upgradeInfo;